我想知道如何使用Ramda Lenses更改对象属性.

目前,我的状态很深：

buckets[
    blocks[
        messages[
            replies [
                {id: 0, text: 'text 0', value: 'simple value 0'},
                {id: 1, text: 'text 1', value: 'simple value 1'},
                {id: 2, text: 'text 2', value: 'simple value 2'},
                ...
            ]
        ]
    ]
]

我有一个基本的有效载荷.我想获取属性和值,并在我的状态下用新值设置旧值,例如使用此有效负载：

{text: ‘new_text’}
or
{value: ‘new_value’}

在我的减速器中,我有：

case SEQUENCES.UPDATE_REPLY_ON_BLOCK :
// payload => {text: 'new_text'}, or {value: 'new_value'}, or anyway...

let key = Object.keys(payload)[0];
let value = payload[key];

return R.over(
  R.lensPath(["buckets", 0, "blocks", 0, "messages", 0, "replies", 0, key]),
  R.set(value),
  state
);

我尝试了Merge：

return R.over(
    R.lensPath(["buckets", 0, "blocks", 0, "messages", 0, "replies", 0),
    R.merge(payload),
    state,
);

但结果相同：状态未修改,我没有错误.

Maybe SOLVED with mergeDeepLeft :

//payload => {value: 'new_value'}

return R.over(
    R.lensPath(["buckets", 0, "blocks", 0, "messages", 0, "replies", 0),
    R.mergeDeepLeft(payload),
    state,
);

解决方法:

你近了问题是R.set和R.over用于两个不同的任务.您不需要在这里.相反,应该设置外部功能,第二个参数是要将镜头设置为的值：

const payload = {text: 'new_text'}
const key = Object.keys(payload)[0];
const value = payload[key];

const state = {buckets: [{blocks: [{messages: [{replies: [{id: 0, text: 'text 0', value: 'simple value 0'}, {id: 1, text: 'text 1', value: 'simple value 1'}, {id: 2, text: 'text 2', value: 'simple value 2'}]}]}]}]}

console.log(
    R.set(
        R.lensPath(['buckets', 0, 'blocks', 0, 'messages', 0, 'replies', 0, key]),
        value,
        state,
    )
)

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.js"></script>

当您要基于已经存在的值进行调整时,可以使用over,将函数从旧值传递到新值作为第二个参数.例如,R.over(myLens,R.toUpper,obj)：

const payload = {text: 'new_text'}
const key = Object.keys(payload)[0];
const value = payload[key];

const state = {buckets: [{blocks: [{messages: [{replies: [{id: 0, text: 'text 0', value: 'simple value 0'}, {id: 1, text: 'text 1', value: 'simple value 1'}, {id: 2, text: 'text 2', value: 'simple value 2'}]}]}]}]}

console.log(
    R.over(
        R.lensPath(['buckets', 0, 'blocks', 0, 'messages', 0, 'replies', 0, key]),
        R.toUpper,
        state,
    )
)

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.js"></script>